Chest Film Findings

The chest film abnormalities depend on the age of the patient and the severity of the stenosis. In infancy, pulmonary edema with generalized cardiomegaly is the typical appearance of obstruction to blood flow at any point between the pulmonary veins, left heart, and aorta (Fig. 6-2). The adult heart is normal in size, and the lungs are clear unless there is left ventricular failure and dilatation (Fig. 6-3). Calcification in the aortic valve over age 40 years occurs in all types of aortic stenosis and clinically marks the stenosis as severe. Dilatation of the ascending aorta is frequent in aortic stenosis but correlates rather poorly with severity or with the site of the stenosis (one third of patients with subvalvular aortic stenosis have dilated aortas).

FIGURE 6-2 Aortic stenosis in the infant. The heart is globally enlarged with leftward dilatation of the apex. The large left atrium has a double density (arrow) that projects into the lung. The pulmonary hila have mild edema.

FIGURE 6-3 Aortic stenosis in the adult. A, The heart size is normal and the lungs are clear. The ascending aorta (arrow) is mildly dilated. B, The aortic valve (arrow) is irregularly calcified.

Imaging Features

Leaflet motion will be abnormal if there is deformity, fibrosis, or calcification. A slow opening and closing of the leaflets and a domed appearance indicate thickening and deformity. In general, complete visibility of the leaflets in systole indicates an abnormality because normal leaflets, if visible, are less than 1 mm in width.

The preferred imaging modality for the dynamic assessment of aortic stenosis remains echocardiography. Cardiac-gated multidetector CT (MDCT) angiography is proving to be an excellent modality to detect and quantify aortic valve stenosis. Direct planimetry of the valve opening in systole correlates quite well to echocardiographic grades of aortic stenosis severity. The added advantage of MDCT is that it nicely demonstrates associated aortic root pathologies. Fig. 6-4 shows a case of mild aortic stenosis with the valve in short axis during systole (open) and diastole (closed). Fig. 6-5 shows the same valve in long axis during systole and diastole. Finally, MRI can be useful for aortic stenosis because it can accurately quantify peak aortic valve velocities and pressure gradients. The associated calcium on the valve makes MRI less useful to assess morphology because of the typical signal loss of calcified structures on gradient echo pulse sequences. A narrow orifice to the aortic valve is visible as a jet through the valve. The degree of aortic stenosis can be estimated by comparing the width of the jet with the diameter of the aortic annulus. When the jet is less than 15% of the diameter of the annulus, there is severe aortic stenosis. However, it may also be present when the width of the column of blood through the valve appears to be the same size as the annulus. This latter finding is typical of degenerative aortic stenosis in the elderly and in many cases of rheumatic involvement of the aortic valve. In the former, the valve orifice is irregularly eccentric without commissural fusion, allowing the stream of contrast material adjacent to the three commissures to project over the entire width of the aorta. Calcification may be so extensive that the leaflets are akinetic.

FIGURE 6-4 Aortic valve in cross section. A, A trileaflet aortic valve image with multiplanar reformat cardiac-gated multidetector computed tomography during systole shows that the noncoronary cusp and left coronary cusp are partially fused (arrow) with restriction of leaflet opening. Planimetry of the valve area can be performed to determine the valve area. B, Diastolic image shows the calcified noncoronary cusp (arrow).

FIGURE 6-5 Three-chamber long-axis view of the aortic valve. A, In systole, the leaflets are incompletely open. The noncoronary cusp (arrow) is nearly immobile. B, In diastole, note the calcified atheromatous disease (arrowheads) in the ascending aorta.

Poststenotic dilatation of the ascending aorta results from the jet through the valve striking the lateral aortic wall. The lateral wall of the aorta becomes both dilated and elongated, further accentuating the rightward displacement of the aorta into the right lung. Poststenotic dilatation occurs in 25% of patients with subvalvular aortic stenosis. By its nature, supravalvular stenosis does not involve dilatation of the aorta. As a rule, a poststenotic dilatation can be correlated with the location (i.e., valvular) but not with the severity of the aortic stenosis. Poststenotic dilatation occurs in all age groups, even neonates.

In most children and adults with pure, severe aortic stenosis, the left ventricle has a small cavity that is hypercontractile and has the usual signs of hypertrophy. In the absence of other anomalies, left ventricular dilatation in pure aortic stenosis is direct evidence of heart failure, a complication that is particularly critical in neonates. In this condition, the left ventricle usually exhibits diffuse hypokinesis with an increased end-diastolic volume and low ejection fraction. In severe heart failure, segmental wall motion abnormalities occur in the absence of coronary disease, particularly in the anterior and lateral segments.

Box 6-1 lists the causes of aortic stenosis.

Congenital Valvular Aortic Stenosis

The bicuspid aortic valve is the most common congenital cardiac malformation, occurring in 0.5% to 2.0% of the population. This malformation is usually not stenotic during infancy (although it may be so) but may become stenotic as fibrosis and calcification occur. Bicuspid valves can be either stenotic, regurgitant, or both. There is infective endocarditis in 75% of those with pure regurgitation.

Distinctive calcifications on the lateral chest film characterize the congenital bicuspid aortic valve. Calcium is visible in the raphe of the valve and in the line of insertion of the shallow conjoint leaflet and the convex nonfused leaflet (Fig. 6-6). An acquired cause of a bicuspid valve is fusion of the commissures of the aortic leaflets in rheumatic heart disease.

FIGURE 6-6 Calcified bicuspid aortic valve. A, Dense calcifications in the heart lie on a line drawn between the sternodiaphragmatic angle and the carina locating the calcium to be in the aortic valve. B, Magnification view shows the ring of calcium and the central raphe (arrow).

The angiographic appearance of a congenital bicuspid valve is two sinuses of Valsalva and two leaflets (Fig. 6-7). The valve orifice may be oriented in either an anteroposterior direction, which divides the leaflets into right and left cusps, or in a right-left direction, dividing the valve into anterior and posterior leaflets. If the cusps are on the right and left, there may be a raphe in the right cusp, and each sinus of Valsalva gives origin to a coronary artery. If the cusps are anterior and posterior, a raphe, if present, occurs in the anterior cusp, and both the coronary arteries arise from the anterior sinus of Valsalva. The normal aortic valve may acquire a bicuspid appearance when one commissure fuses as a result of rheumatic heart disease. In general, the congenital bicuspid valve will have one of the sinuses of Valsalva and its leaflet occupying half the circumference of the aortic annulus, whereas the acquired bicuspid valve with one fused commissure still demonstrates three sinuses of Valsalva of nearly equal size. In diastole, the congenital bicuspid valve may appear to have three sinuses of Valsalva because the raphe is visible and divides one of the two leaflets in half.

FIGURE 6-7 Congenital bicuspid aortic valve. A, In systole, the two leaflets and their sinuses of Valsalva are best visualized in the left anterior oblique projection. B, In diastole, three sinuses of Valsalva are visible, one of these actually representing a single sinus with a raphe (arrows).

The congenital bicuspid aortic valve is recognizable most accurately during systole. The systolic appearance of a noncalcified congenital bicuspid valve typically includes domed and thickened leaflets (Fig. 6-8). The jet through the valve is usually slightly eccentric in direction but appears through the central part of the aortic annulus. In contrast, the jet through the rare unicommissural valve is quite eccentric.

FIGURE 6-8 Congenital aortic stenosis. The aortic leaflets (arrows) are domed and have a jet of contrast medium through them. More than half of the left ventricular cavity is obliterated. The aortic gradient was 90 mm Hg.

MDCT can be quite useful at characterizing congenital bicuspid aortic valves. Fig. 6-9 depicts a congenital bicuspid aortic valve in systole on MDCT in cross section and long axis, respectively. This patient has a normal systolic opening area with classic systolic dooming. Fig. 6-10 is a different case of a bicuspid aortic valve on MDCT. This valve demonstrates calcification of the cusps and diastolic prolapse. Cardiac MRI is more limited at depicting aortic valve leaflet morphology because the associated leaflet calcium causes profound signal void on MRI gradient pulse sequences, such as in Fig. 6-11. Black blood MRI pulse sequences may overcome this artifact.

FIGURE 6-9 Bicuspid aortic valve. A, Multiplanar reformat cardiac-gated multidetector computed tomography (MDCT) of a bicuspid aortic valve in cross section during systole. MDCT can clearly depict both cusps. The systolic opening area in this patient is normal and the patient has not yet developed aortic valve stenosis. B, Three-chamber long-axis view of the same valve during systole showing the classic systolic doming (arrowheads).

FIGURE 6-10 Congenital bicuspid valve. This example demonstrates calcification of the valve leaflets (arrowheads) and diastolic prolapse in this three-chamber long-axis view of the valve.

FIGURE 6-11 Magnetic resonance imaging (MRI) cine steady state free precession (SSFP) of a bicuspid aortic valve. A, In cross section the cusps are calcified, which is the cause for the considerable signal void. MRI has a limiting use for characterizing the leaflet morphology. B, MRI black blood of the same bicuspid valve in long axis during systole. The thickened cusps are thickened and domed (arrowheads).

Bicuspid aortic valves are associated with many types of congenital heart disease. Half of those with coarctation of the aorta have a bicuspid aortic valve (Fig. 6-12). More generally, any malformation of the aorta, such as aortic arch atresia or interruption or the hypoplastic left heart syndrome, has a high incidence of bicuspid aortic valve.

FIGURE 6-12 Coarctation of the aorta and bicuspid aortic valve. The narrow jet through the valve indicates severe stenosis. Note that the jet hits the opposite wall of the ascending aorta, a cause of later poststenotic dilatation.

The congenital unicuspid aortic valve is intrinsically stenotic and may at times be incompetent. This valve may exist with no lateral attachments and appear as a diaphragm with a central opening. A second type of unicuspid valve has one lateral attachment to the aortic annulus with the commissure appearing as a raphe between the central point and the aortic wall. Both types of valve are rare. In systole, there is an eccentric jet against the posterior wall of the aorta with no leaflet tissue posteriorly. In diastole, a sinus of Valsalva may appear anteriorly but not posteriorly.

Acquired Valvular Aortic Stenosis

The aortic valve that is not stenotic at birth may become so in two ways:

The end stage of any of these processes is a severely calcified valve, and it may be impossible to determine the initial process. In the extreme, the leaflets may be so thickened as to be akinetic. Unlike the congenital, noncalcified bicuspid aortic valve, these end-stage valves usually do not have a jet through them (Figure 6-13). The stream of contrast medium or blood through the distorted and curved linear orifice is turbulent. Doming of the leaflets is always seen in the noncalcified congenital aortic stenosis but is an inconstant feature in an end-stage aortic valve.

FIGURE 6-13 Calcific aortic stenosis. Severe aortic stenosis exists, although the leaflets are poorly seen and no jet of contrast media passes through the valve. The large papillary muscles and distorted cavity represent moderate left ventricular hypertrophy.

Calcific aortic stenosis in the adult results from rheumatic heart disease, occurs on a congenital bicuspid aortic valve, and occurs in the elderly. Although some overlap occurs, you can differentiate these three conditions by age and by the presence of other valvular lesions. The congenital bicuspid aortic valve begins to calcify in the fourth decade, whereas degenerative aortic stenosis affects those over 65 years of age. In developing countries, calcification in rheumatic aortic stenosis may appear in the late teens, but it is unusual in the United States until the fourth decade. With the aortic stenosis of rheumatic heart disease, mitral stenosis does not occur for at least 7 to 10 years after an episode of acute rheumatic fever, and aortic stenosis may develop about 7 years after that.

An important clue to the diagnosis of rheumatic disease in the aortic valve is the presence of mitral stenosis or regurgitation and calcification or thickening in the mitral leaflets in an otherwise functional valve. One characteristic of rheumatic aortic stenosis is the fusion of the commissures adjacent to the aortic wall. In general, these valves have either the usual appearance of a tricuspid valve or have one distorted sinus of Valsalva that occupies more than half the aortic annular circumference. When there is fusion of multiple commissures, the leaflets are usually so thickened and distorted that valve morphology is indistinguishable from other types of aortic stenosis.

Aortic stenosis in the elderly results from degeneration of the valve leaflets with subsequent thickening and calcification. Some patients have coronary calcification and calcification in the mitral annulus and in the aortic arch. These aortic valves are tricuspid and have clumps of calcium within the webs of the leaflets. In contrast to rheumatic valves, the commissures are not fused (Fig. 6-14).

FIGURE 6-14 Aortic stenosis in an elderly patient without a jet through the valve. Supravalvular aortogram in systole shows a tricuspid valve without commissural fusion. Moderate calcium was present in the leaflets. The left ventricle is faintly outlined by mild aortic regurgitation.

MDCT can image calcific degenerative aortic valve stenosis (Figures 6-15, (6-16). The valve area can be planimetered from the short-axis views.

FIGURE 6-15 Severe degenerative aortic valve stenosis in an elderly patient. Three-chamber long-axis view of the valve with severely narrowed systolic opening of the valve cusps (arrow).

FIGURE 6-16 Same valve and view in Figure 6-15. The left ventricular walls are mildly hypertrophied with more focal thickening of the basal septum. Note focal hypertrophy of the basal septum (arrowheads) that may be a consequence of pressure overload from the aortic valve stenosis.

Pathologic Abnormalities

Subvalvular aortic stenosis, or subaortic stenosis, consists of a heterogeneous group of abnormalities, several of which are associated with other types of cardiac malformation. These obstructions include:

Angiographic Findings

Optimal visualization of the angiographic features of most of these conditions is possible with biplane left ventriculography with cranial angulation in the left oblique projection. Because several of these malformations may be quite subtle (particularly discrete membranous subaortic stenosis), standard ventriculography may not demonstrate a lesion that is quite evident on pressure tracings. In these instances, an aortic root injection is useful because many of these valves are incompetent and the regurgitant stream outlines the subaortic chamber (Fig. 6-17). A magnetic resonance scan in planes aligned to the cardiac axis can sort out subaortic complexities with tomographic imaging (Fig. 6-18).

FIGURE 6-17 Subaortic membrane demonstrated with an aortogram. The aortic regurgitation outlines the membrane (arrow) and fills the left ventricle.

FIGURE 6-18 Membranous and fibromuscular subaortic stenosis. A, A thin membrane (black arrow) is present about 1 cm below the right aortic cusp (white arrow). B, A subaortic conical narrowing represents the fibromuscular component.

(From Miller SW, et al.: Cardiac magnetic resonance imaging: The Massachusetts General Hospital experience, Radiol Clin North Am 23:745-764, 1985.)

About 15% of patients with congenital obstruction to left ventricular outflow have discrete membranous subaortic stenosis. This consists of a 1- to 4-mm-thick membrane below the aortic valve. The membrane varies in position from just below the aortic valve to about 4 cm beneath it. The membrane may attach to the anterior leaflet of the mitral valve, and strands from this membrane may extend to the aortic cusps (Fig. 6-19). About one third to half of these patients have aortic insufficiency, and fewer than 5% have mild mitral insufficiency.

FIGURE 6-19 Discrete membranous subaortic stenosis. Cranial angulation in the left anterior oblique projection outlines of linear lucency (arrow) below the aortic leaflets, extending from the septum to the mitral valve.

In membranous subaortic stenosis, the true aortic leaflets usually have an abnormal appearance and motion. Unless there is also valvular stenosis, the leaflets are not domed but usually are mildly thickened and may have an irregular surface. The jet through the subvalvular membrane must also pass through the aortic leaflets, generating considerable turbulence. The aortic leaflets typically have an incomplete opening and may partially close in mid systole before finally attaining the maximum orifice size. In general, one will often see a subvalvular jet extending through the aortic leaflets if the obstruction is just beneath the aortic valve. It becomes less visible or may be absent if the obstruction lies at a lower level.

In tunnel subaortic stenosis, the obstruction extends 1 to 3 cm below the aortic annulus. One type is a fibromuscular bar extending near or on to the anterior leaflet of the mitral valve. Another type has a long conical narrowing in the subaortic region with little change between systole and diastole (Fig. 6-20). The left ventricle shows the usual signs of hypertrophy, but occasionally this overgrowth of muscle may produce bizarre shapes.

FIGURE 6-20 Tunnel subaortic stenosis. A, A conical narrowing (arrows) in the long axial oblique projection persisted unchanged throughout the cardiac cycle. The aortic leaflets are thick. Moderate supravalvular stenosis is also present. B, A fibromuscular subaortic stenosis (arrows) is complicated anteriorly by a membrane and posteriorly by a slight systolic anterior motion of the anterior leaflet of the mitral valve.

Idiopathic hypertrophic subaortic stenosis (discussed in Chapter 9) is a dynamic form of subaortic stenosis. The obstruction occurs in systole with the abnormal anterior systolic motion of the anterior leaflet of the mitral valve. During diastole, the stenosis disappears as the mitral leaflet resumes its normal position. A similar dynamic subvalvular stenosis may be seen in transposition of the great arteries. Here the mitral leaflet creates a subpulmonary stenosis as the left ventricle is connected to the pulmonary artery.

Subaortic Obstruction

Subaortic obstruction may rarely result from valve abnormalities or malalignment defects in complex congenital heart disease. Accessory mitral valve tissue, anomalous attachment of the mitral valve and its chordae tendineae, or a displaced annular insertion of the anterior leaflet result in outflow obstruction. The angiographic findings with each of these abnormalities varies; however, an asymmetric filling defect that moves into the subaortic region during systole and returns to a more posterior and inferior location during diastole is often visible during left ventriculography. Other complex congenital malformations have subaortic obstruction with conoventricular malalignment (e.g., aortic atresia and ventricular septal defect and in transposition with the aorta originating above an infundibular chamber).

Classifications

There are three types of supravalvular stenosis. The hourglass type consists of a narrow segment of the ascending aorta just distal to the origin of the coronary arteries (Fig. 6-21). The second type is a membrane or fibrous diaphragm at the sinotubular aortic junction. The least common is hypoplasia of the entire ascending aorta from the sinotubular junction to the origin of the brachiocephalic artery (Figure 6-22). In actual practice, these three forms overlap and are alternatively classified as discrete or diffuse stenoses, categories that correspond to the alternatives in surgical treatment.

FIGURE 6-21 Supravalvular aortic stenosis. Hour-glass type of supravalvular aortic stenosis shows large sinuses of Valsalva and large coronary arteries.

FIGURE 6-22 Supravalvular aortic stenosis. A, Coronal magnetic resonance imaging shows the hypoplastic aorta (crosses) beginning above the aortic root. B, The hypoplastic left heart syndrome has a ventricular septal defect with absence of the inferior half of the septum.

Associated Lesions

Associated cardiac lesions occur in two thirds of patients with supravalvular aortic stenosis. Common abnormalities are hypoplastic aortic valve annulus and valvular aortic stenosis. Some of these patients are part of a generalized disorder associated with hypercalcemia in infancy, elfin facies, and stenoses in other arteries (Williams syndrome).

Associated findings in supravalvular aortic stenosis are:

The coronary arteries are proximal to the obstruction and are subject to elevated left ventricular systolic pressure from birth, making them both dilated and tortuous.

Chest Film Findings

If the aortic regurgitation is both chronic and severe, the chest film hallmarks are left ventricular enlargement and dilatation of the entire aorta (Fig. 6-23). This pattern follows the principle that regurgitation of any of the heart valves enlarges structures on both sides of the insufficient valve. If the regurgitation is acute, signs of left ventricular failure are present—pulmonary edema and pleural effusions. Then, after several days, the left ventricle is visibly dilated.

FIGURE 6-23 Chest film in chronic severe aortic regurgitation. Structures on both sides of the regurgitant valve are large, reflecting the high-output state: the left ventricle and the entire thoracic aorta.

Angiographic Technique

The angiographic examination should demonstrate the insufficient valve, allow quantitation of the regurgitant volume, and demonstrate the pathologic changes. If there is moderate regurgitation, left ventricular volume and the ejection fraction may also be computed.

The typical examination is a biplane supravalvular aortogram performed in both oblique projections. The injection rate varies, depending on patient age, the size of the ascending aorta, and the clinical judgment of the severity of the runoff. For example, in the adult with suspected severe aortic regurgitation, an injection rate of 35 to 40 ml/sec over 2 seconds gives good visualization. Analysis of cuspal motion necessitates the cine technique.

Magnetic Resonance Imaging Technique

Cine MRI and color flow Doppler ultrasound can identify and quantify valvular regurgitation. On both techniques, the imaging plane is rotated to include the aortic root and the regurgitant jet. Cine MRI (gradient-refocused MRI), a “white blood” technique, is set up to provide repetitive loops of a cardiac cycle with both magnitude and phase reconstruction. Aortic regurgitation is identified as a discrete area of signal loss coming from the aortic valve into the left ventricle during diastole (Figure 6-24).

FIGURE 6-24 Aortic regurgitation imaged with cine magnetic resonance imaging. A, The signal void (arrow) in the diastolic frame is the jet of aortic regurgitation into the left ventricular (LV) outflow region. B, In the systolic frame, the aortic valve (A) region has normal forward flow, but the leaflets are thick. The linear lucency in the aortic root is an intimal flap of a dissection.

Subjective assessment of the amount of regurgitation is clinically useful to plan therapy. Medical treatment with afterload-reducing agents is commonly prescribed for mild to moderate regurgitation, whereas surgical valve replacement is needed for severe regurgitation. Under these circumstances, the following grading system is the standard of practice to assess aortic regurgitation:

Imaging Findings

Stenotic valves, vegetations, and prolapse of one of the cusps are easy to identify, whereas perforation of a cusp is rarely visible directly. The regurgitant jet into the left ventricle is visible on an MRI, ultrasound, or angiographic study. Aortic root abscesses and aortic dissection in the root produce an unstable aortic annulus but may leave the leaflets intact. A paravalvular regurgitation around a prosthetic valve can result from endocarditis in the aortic root or with dehiscence of part of the valve ring. Dilatation of the aorta itself may enlarge the aortic annulus so that the leaflets do not coapt. Giant cell aortitis and connective tissue diseases typically dilate the aorta so that mild regurgitation ensues. Severe regurgitation more commonly results from cystic medial necrosis in which both the aortic root and ascending aorta have an aneurysmal pear shape with obliteration of the sinotubular junction.

Specific Causes of Aortic Regurgitation

When the aortic valve is incompetent, the differential diagnosis is either a condition that primarily affects the aortic valve or one that secondarily results from a disease in the ascending aorta.

Fibrosis from the valvulitis in rheumatic heart disease is the most common aortic valve abnormality that causes regurgitation. These valves have thickened cusps that are shortened by the fibrotic process and may have some commissural fusion. Depending on the severity of the rheumatic process, the leaflets may have no visible calcium or, conversely, they may be reduced to irregular lumps with poor motion. The regurgitant jet is usually central unless the valve commissures are fused asymmetrically. In degenerative aortic valve disease, which occurs in persons over age 65, the cusps are thickened and immobile but without commissural fusion. Then regurgitation occurs over a broad front that is essentially the same diameter as the aortic annulus (Fig. 6-27). Fine fluttering of the anterior leaflet of the mitral valve is occasionally visible if the aortic regurgitation is severe.

FIGURE 6-27 Aortic regurgitation in degenerative aortic valve disease of the elderly. Supravalvular aortogram shows three leaflets without commissural fusion. The valve is moderately calcified. The aortic regurgitation is moderate (grade 3).

Infective endocarditis can lead to aortic regurgitation with either perforation of a cusp (Fig. 6-28) or prolapse of an aortic cusp from destruction of the adjacent annulus (Fig. 6-29).

FIGURE 6-28 Aortic root abscess. Left anterior oblique aortogram shows a small collection of contrast media (arrow) in the subaortic region. The aortic regurgitation is severe.

FIGURE 6-29 Ventricular septal defect. Ventricular septal defect resulting from an abscess in the aortic root extending into the interventricular septum. Note the prosthetic aortic valve in the middle of the large aortic root abscess that has destroyed the upper ventricular septum. Regurgitation occurs into both the right (RV) and left (LV) ventricles.

Common consequences of aortic valve infective endocarditis are:

Prolapse of one or more cusps appears in several acquired and congenital lesions. The aortic cusps in Marfan syndrome (rarely, in other diseases of elastic tissue) are large with deep sinuses of Valsalva and laxity in their supporting structures. Eversion of an aortic cusp into the left ventricle occurs in about 5% of ventricular septal defects in which the right or the noncoronary leaflet becomes adherent to the superior margin of the septal defect (Fig. 6-30). In a traumatic tear of the aortic root and in aortic dissection, the supporting points of the leaflets may become unhinged from the annulus and then prolapse. With more severe loss of support, the leaflets can be flail with coarse vibrations in the regurgitant stream.

FIGURE 6-30 Ventricular septal defect. Prolapse of the right aortic cusp (arrows) resulting from fibrous adhesions pulling the leaflet into a closing ventricular septal defect. Mild aortic regurgitation is present. The cineangiogram in the right (A) and left (B) anterior oblique projections shows faint aortic regurgitation and opacification of the pulmonary artery from passage of contrast across the ventricular septal defect.

Most stenotic valves usually have an element of regurgitation. The congenital bicuspid aortic valve may be the cause of severe regurgitation with or without stenosis. Infective endocarditis is a prime concern in patients with known bicuspid valves and new-onset aortic regurgitation.

Primary diseases of the ascending aorta that cause dilatation, such as ankylosing spondylitis and rheumatoid arthritis, may also enlarge the orifice of the aortic valve. Cystic medial necrosis of the aorta produces regurgitation by similar mechanisms, with or without annuloaortic ectasia and dissection (Fig. 6-31). In syphilitic aortitis, the cause of regurgitation may be purely the result of the rolled and thickened edges of the aortic valve or from aneurysms of the sinuses of Valsalva or other adjacent structures.

FIGURE 6-31 Torn leaflet from a dissection. The intimal flap of the aortic dissection has ripped a cusp from the aortic annulus and caused moderate regurgitation.

Prosthetic Aortic Valves

Regurgitation after cardiac valve replacement may be of two kinds: valvular or paravalvular. Growth of scar tissue into the valve may prevent the ball or disk from seating completely, thus causing regurgitation through the valve. In porcine valves, the leaflets may degenerate or perforate. The regurgitant jet occurs through the prosthesis with an eccentric jet. Paravalvular regurgitation is seen as contrast material beside the sewing ring. The usual cause of late paravalvular regurgitation, and in fact a possibility at any time after valve replacement, is prosthetic endocarditis. When this occurs, the angiographic findings are a fistula between the sinuses of Valsalva and the left ventricle and pseudoaneurysms adjacent to the prosthesis (Fig. 6-32). Vegetations may extend into the valve and cause decreased motion of the leaflets.

FIGURE 6-32 Pseudoaneurysm in the aortic root after valve replacement. In the left anterior oblique projection a pseudoaneurysm (arrow) is seen near the anterior aspect of the aortic root; this abscess is in the upper part of the ventricular septum. The left ventricle (LV) is mildly opacified by both valvular and paravalvular regurgitation.

Chest Film Findings

The chest film in mitral stenosis physiologically reflects the left atrial hypertension. There are signs of left atrial enlargement but the left ventricle is normal in size. In the child with a hypoplastic left heart syndrome and congenital mitral stenosis, there is an enlarged heart and pulmonary edema. In the adult with rheumatic heart disease, the onset of mitral thickening and chordal scarring and retraction occurs over such a long period that the lungs have made adaptive changes in the walls of the pulmonary arteries and veins. The lungs have an interstitial pattern that is probably part fibrosis and part edema. Pulmonary edema is visible as an interstitial pattern but not as an acinar pattern, unless there is a complication such as an infected or thrombosed valve. Patients with severe mitral stenosis may rarely have hemoptysis. The site of bleeding is probably in the engorged plexus of vessels around the middle to smaller bronchi. A late sequela of the bleeding is the development of hemosiderosis (Fig. 6-36). These deposits may ossify.

FIGURE 6-36 Hemosiderosis in mitral stenosis. A, Nodular pattern with Kerley B lines. B, Segmental dense acinar opacities.

Calcification in the mitral valve is nodular and amorphous. The amount of calcium roughly correlates with the degree of mitral stenosis but, unlike the aortic valve, the mitral valve may be severely stenotic and have no radiologically visible calcification (Fig. 6-37). As a late sequela to the inflammatory carditis in acute rheumatic fever, the left atrium may calcify (Fig. 6-38). These patients have long-standing atrial fibrillation and are at risk for left atrial thrombus and emboli.

FIGURE 6-37 Mitral leaflet calcification in mitral stenosis. This calcification (arrow) is more easily seen on the lateral chest film because it overlaps the spine on the posteroanterior film. Note barium in the esophagus is pushed posteriorly by the enlarged left atrium.

FIGURE 6-38 Left atrial calcification (white arrows). The mitral valve (black arrow) is calcified and the left bronchus is displaced posteriorly.

Cardiac-Gated Multidetector Computed Tomography

MDCT is an accurate tool to assess mitral valve calcium and leaflet morphology. It is proving to be a feasible, accurate, and reliable tool for the determination of mitral valve area with echocardiographic as a reference standard. Valve area assessment requires using multiplanar reformats to create a true cross section through the mitral valve tips in early mid diastole followed by direct planimetry of the opening area.

Imaging Approach to Mitral Stenosis

You will usually use echocardiography to evaluate abnormalities of the mitral valve. As discussed in Chapter 2, the area of the mitral orifice is measured by ultrasound, and the salient characteristics of mitral stenosis are graded: calcification and mobility in the valve, submitral scarring, and leaflet thickening. Left ventriculography (Fig. 6-39) is needed before percutaneous mitral valvuloplasty to grade mitral regurgitation because moderate to severe regurgitation precludes the procedure. Occasionally, pulmonary arteriogram or a left atrial injection through a patent foramen ovale helps evaluate suspected abnormalities on the left atrial side of the mitral valve. Of course, you should not use a left atrial injection from a transseptal approach if you suspect a myxoma or a thrombus because the procedure can dislodge emboli.

FIGURE 6-39 Rheumatic mitral stenosis. The mitral valve in diastole is incompletely opened (domed) from commissural fusion. The rounded anterolateral wall and flat inferior wall are typical of right ventricular dilatation that compresses the left ventricle.

Rheumatic Mitral Stenosis

The hallmarks of mitral stenosis are the calcified, hypokinetic, and domed mitral leaflets. In severe mitral stenosis, the left atrium is always large and the left ventricle is smaller than normal with a slightly decreased ejection fraction. The doming of the leaflets signals a stenotic valve. Fusion of the commissures is not directly visible, but the leaflet doming and the jet of unopacified blood in the left ventricle are indirect signs of the stenotic orifice. The leaflets are thickened and slightly nodular and appear to attach directly to the papillary muscle.

Retraction and scarring of the chordae tendineae may result in a subvalvular mass that mimics vegetations. The subvalvular scarring, particularly that involving the posteromedial papillary muscle, appears to pull this muscle toward the base of the left ventricle (Fig. 6-40). Subvalvular scarring itself can produce substantial mitral stenosis.

FIGURE 6-40 Subvalvular fibrosis in mitral stenosis. Moderate retraction of the tip of the papillary muscle (arrow) toward the mitral leaflets. Severe fibrosis has caused a tumorlike mass consisting of matted chordae tendineae and the posteromedial papillary muscle. There is moderate mitral regurgitation into a large left atrium.

Less common causes of obstruction about the mitral valve include left atrial myxomas and “ball valve” thrombi, which originate in the left atrium and prolapse through the mitral valve during diastole and thus obstruct it. Processes outside the heart (constrictive pericarditis or adjacent mediastinal masses) can press on and distort the mitral valve and cause extrinsic mitral stenosis.

Congenital Abnormalities Causing Left Ventricular Inflow Obstruction

Congenital types of left ventricular inflow obstruction result from malformations in the mitral valve, the left atrium (cor triatriatum), or rarely, in the pulmonary veins (pulmonary venous hypoplasia or atresia). When associated with other abnormalities of the left ventricle, aortic valve, and aorta, the term hypoplastic left heart syndrome is appropriate.

Cor Triatriatum

Cor triatriatum is an anomaly in which the left atrium and the mitral valve are divided from the confluence of pulmonary veins by a constriction. The communication between the accessory chamber, which is the confluence of pulmonary veins, and the true left atrium is a diaphragm or membrane containing either single or multiple orifices. A tubular constriction between the common pulmonary veins and the left atrium may also be found in cor triatriatum.

In most patients with this anomaly, the mitral valve, left atrial appendage, and fossa ovalis (secundum atrial septal defect) are associated with the true left atrial cavity. A catheter entering the right atrium would pass through an atrial septal defect into the true left atrium adjacent to the mitral valve. Exceptions exist, however, so that the foramen ovalis may connect the right atrium with the accessory chamber receiving the pulmonary veins. Partial anomalous pulmonary venous connections are frequent. Cor triatriatum can occur as an isolated anomaly but occurs frequently with ventricular septal defects, coarctation of the aorta, or a common atrioventricular canal defect.

The chest film shows pulmonary venous hypertension and an enlarged heart. An angiogram with the catheter through the patent foramen ovale shows a distorted, small atrial chamber without visualization of the pulmonary veins or their connections with the heart (Fig. 6-41).

FIGURE 6-41 Cor triatriatum. A, Mitral regurgitation during a left ventriculogram outlines the left side of the membrane (arrow) of the cor triatriatum and the appendage of the left atrium. B, The venous phase of a right pulmonary arteriogram shows the right side of the membrane (arrow) and the connection with the pulmonary veins.

Congenital Mitral Stenosis—Hypoplastic Left Heart Syndrome

Congenital mitral stenosis is an uncommon malformation and comprises several anatomic types. Typical congenital mitral stenosis consists of obstruction by the leaflets and their chordal attachments. The leaflets are thickened and bulge into the left ventricular cavity during diastole (Fig. 6-42). There are two papillary muscles that have reduced interpapillary distance; the left ventricle is normal in size. Another type of mitral obstruction is a supramitral ring that originates on the left atrial side of the mitral valve as accessory tissue above and adjacent to the mitral orifice. In the parachute mitral valve, a single papillary muscle is present that receives all the chordae. This single papillary muscle is visible as a filling defect within the left ventricle on its inferior surface. The mitral leaflets are thickened and deformed and may show eccentric doming. Shone syndrome consists of the parachute mitral valve, supravalvular ring of the left atrium, subaortic stenosis, and coarctation of the aorta. A hypoplastic mitral valve associated with hypoplasia of the remainder of the left side of the heart characterizes the hypoplastic left heart syndrome. This can be distinguished from other congenital forms because this type has hypoplasia of all parts of the mitral valve: the leaflets, chordae, papillary muscles, and annulus.

FIGURE 6-42 Congenital mitral stenosis. Two angiographic techniques to visualize the stenotic mitral valve or exclude a cor triatriatum are (A) a left atrial injection with the catheter through the foramen ovale, and (B) a pulmonary artery injection. The transit of contrast through the lungs is prolonged, with unusually good visualization of the pulmonary veins.

Chest Film Findings

The detection of mitral regurgitation on the plain chest film depends on the chronicity and severity of the disease. Acute severe mitral regurgitation causes pulmonary venous hypertension and pulmonary edema but little cardiac dilatation. After several days, as the heart begins to dilate, the lungs also begin to adapt, with intimal hyperplasia and muscular hypertrophy in the arterial and venous walls, so alveolar pulmonary edema regresses and an interstitial pattern appears. After weeks to months of chronic mitral regurgitation, the left atrium and left ventricle are enlarged. The pulmonary pattern is quite variable and may range from a normal vascular pattern through cephalization of flow to signs of interstitial lung disease. There are occasionally Kerley B lines. In long-standing mitral regurgitation, particularly from a rheumatic cause, the pulmonary pattern has a poor correlation with the actual amount of regurgitation.

Angiographic Evaluation

The object of imaging in mitral regurgitation is to identify its cause and to grade the severity. Echocardiography is the method of choice to look at the valve leaflets. Echocardiography and MRI can detect mitral regurgitation with great sensitivity but left ventriculography mainly is used to grade the severity. Angiographic assessment is based on how much contrast flows into the left atrium and how long it takes to flow out:

Cardiac-Gated Multidetector Computed Tomography

The majority of mitral valve leaflet pathology that causes regurgitation can be detected by MDCT. One of the few etiologies that may be missed is chordal rupture. In a concept similar to aortic regurgitation assessment, the central anatomic regurgitant orifice area can be visualized and directly planimetered. The regurgitant orifice area by MDCT compares well to both transesophageal echo Doppler and angiographic evaluation.

Rheumatic Mitral Regurgitation

In acute rheumatic fever with carditis, the major valve lesion is mitral regurgitation; there is no stenosis. The regurgitation may resolve and reappear 5 to 10 years later when mitral stenosis becomes symptomatic. The mitral valve then has calcified, domed leaflets; fusion of the commissures; and short, retracted papillary muscles.

Mitral Valve Prolapse

At first glance mitral prolapse appears to be a leaflet abnormality, but it may encompass all parts of the mitral apparatus. Mitral regurgitation occurs when the cusps and chordae have redundant and exuberant valve tissue. Floppy valves show multiple scallops on the posterior leaflet with elongation of the chordae. Annular dilatation, chordal elongation and rupture, and occasionally, left ventricular contraction abnormalities occur.

There is a roughly 5% incidence of mitral valve prolapse in the general population. There may be mild prolapse in normal hearts, or mitral prolapse associated with severe mitral regurgitation, subacute bacterial endocarditis, chest pain, or rarely, sudden death. Intrinsic mitral prolapse is present from birth, such as that in Marfan syndrome in which both the mitral and tricuspid valves have redundant atrioventricular leaflets. The angiographic hallmark of mitral prolapse during left ventriculography is the passage of the mitral leaflets behind the plane of the mitral annulus into the left atrium. Geometric distortion of the left ventricle, such as right ventricular enlargement that bows the interventricular septum to the left in atrial septal defect, can create moderate prolapse (Fig. 6-43).

FIGURE 6-43 Intrinsic and geometric types of mitral prolapse (arrows). A, The mitral leaflets in Marfan syndrome have an abnormal number of multiple scallops. B, The mitral prolapse associated with atrial septal defect has no scallops (arrow) but is related to the shape of the left ventricle, which is distorted from right ventricular dilatation. After repair of the atrial defect, the prolapse was no longer present.

MDCT can also nicely demonstrate mitral valve prolapse (Fig. 6-44). Diagnostic criteria for mitral valve prolapse on cardiac-gated MDCT are the same as echocardiographic criteria, that is, that the mitral valve leaflets must prolapse beyond the annular plane into the left atrium by greater than 2 mm in the long-axis three-chamber view. The leaflet motion may begin in any scallop of the posterior leaflet or of the anterior leaflet. Then as systole continues, the prolapse proceeds as a posterior curling of the central and free edge of the leaflet. Occasionally, the chordae tendineae are visible as unusually long linear lucencies. The onset of prolapse occurs early in systole and becomes more severe toward the middle and end of systole.

FIGURE 6-44 In this three-chamber view both anterior and posterior mitral valve leaflets are prolapsing into the left atrium during systole (arrowheads).

The degree of mitral regurgitation is obviously a function of the severity of the prolapse. Of those who have severe mitral regurgitation, most have prolapse of the entire posterior leaflet or of both the anterior and posterior leaflets. Prolapse of only one scallop of the posterior leaflet is generally associated only with mild mitral regurgitation. When there is severe regurgitation, particularly with prolapse of an entire leaflet, ruptured chordae are probably present.

Chordal Rupture

In addition to the chordal abnormalities seen in mitral valve prolapse and Marfan syndrome, primary rupture of the chordae tendineae is a common cause of acute mitral regurgitation. Less common malformations include anomalous mitral arcade and other congenital malformations associated with atrioventricular valves. Bacterial endocarditis and rheumatic fever account for roughly half of patients with ruptured chordae. Chordae in the posterior leaflet have a greater propensity to rupture than do those in the anterior leaflet. Because the chordae themselves are rarely visible angiographically, the major features are those of mitral regurgitation and abnormal leaflet motion. The degree of mitral regurgitation depends on the number of ruptured chordae; whether they are primary, secondary, or tertiary chordae; and on the remaining structural support of the mitral leaflet.

Mitral prolapse or flail leaflets occur in more than half of left ventriculograms performed in the clinical setting of chordae rupture (Fig. 6-45). Which leaflet prolapses depends on the location of the ruptured chordae, but in general the posterior leaflet, often the posteromedial scallop, is the more frequent location. A flail leaflet implies rupture of numerous chordae and suggests the possibility of detachment of the head of the papillary muscle. When a flail leaflet occurs, there is an erratic motion of one of the leaflets into the left atrium. The motion of the leaflet is different from beat to beat and frequently has a superimposed high-frequency whipping motion. There is always severe mitral regurgitation.

FIGURE 6-45 Ruptured chordae tendineae with flail leaflets. Both anterior and posterior mitral leaflets prolapse into the left atrium (arrows) with resultant severe regurgitation. The posterior leaflet shows erratic motion.

Papillary Muscle Rupture

Rupture of the head of the papillary muscle commonly results from acute myocardial infarction, although chest trauma, endocarditis, and primary left ventricular muscle diseases may also be culprits. It more frequently involves the posteromedial muscle, possibly because the anterolateral muscle has better collateral circulation. Because each papillary muscle supplies chordae tendineae to both mitral leaflets, rupture of a head of the papillary muscle produces instability in both anterior and posterior leaflets and leads to severe mitral regurgitation. Because the infarct that produces the rupture usually involves a large area of myocardium, the left ventriculogram shows segmental wall motion abnormalities adjacent to the abnormal papillary muscle. These motion abnormalities are conspicuous and range from severe hypokinesis to dyskinesis. The motion of the mitral leaflets ranges from moderate prolapse to flail. The clinical problem is to distinguish this catastrophe from rupture of the interventricular septum.

Papillary Muscle Dysfunction

A myocardial infarct or ischemia in the region of a left ventricular papillary muscle causes a segmental wall abnormality. Akinesis is common but hypokinesis from a non–Q-wave infarct or dyskinesis from an aneurysm is not rare. When these abnormalities involve the segment of the wall with the papillary muscle, the mitral apparatus is maligned and regurgitation occurs. This regurgitation is usually mild unless the papillary muscle is infarcted.

Imaging Complications of Mitral Valve Replacement

Prosthetic valve stenosis, regurgitation, and dysfunction are general indications for postoperative catheterization. Bleeding, tamponade, and myocardial infarction are usually diagnosed by clinical criteria. Prosthetic mitral stenosis is diagnosed by measuring the transvalvular gradient with a catheter in the left ventricle and another in the left atrium. The valve leaflet or disk may not have a full range of motion or may be stuck half-open (Fig. 6-46). Prosthetic mitral regurgitation, depending on the type of valve, may be through the valve or beneath it (Fig. 6-47).

FIGURE 6-46 Prosthetic mitral stenosis. A, A thin layer of thrombus (arrow) on the valve seat limits the mobility of the poppet in the Starr-Edwards valve. B, The tilting disk (arrow) in diastole should open about 80 degrees, but thrombus prevents it from moving beyond 15 degrees.

FIGURE 6-47 Paravalvular mitral regurgitation. Contrast medium flows inferior to the Carpentier-Edwards mitral valve and into the large left atrium.

Chest Film Findings

The chest film findings in pulmonary stenosis are variable and depend on the age of the patient and on associated abnormalities. In the infant, the large thymus may obscure the mediastinum so you can detect the disease only if there is decreased pulmonary flow. In the older child and adult, the classic film of valvular pulmonary stenosis shows mild enlargement of the right ventricle and moderate enlargement of the main and left pulmonary artery (Fig. 6-48). The right pulmonary artery has normal size (Fig. 6-49). In congenital pulmonary stenosis, particularly with hypoplasia of the main pulmonary artery, the pulmonary artery segment is concave. Unless the pulmonary obstruction is so severe as to reduce cardiac output, the overall heart size is normal. In pulmonary valve atresia, with or without an intact ventricular septum, the heart is enlarged, and the cardiac contour is distinctive with right atrial dilatation (Fig. 6-50). The chest film in supravalvular pulmonary stenosis typically shows a straight main pulmonary artery segment and small hilar structures.

FIGURE 6-48 Variations in the pulmonary arteries in valvular pulmonary stenosis. A, Typical appearance is a normal cardiothoracic ratio, convex main pulmonary artery segment, and a dilated left pulmonary artery. B, The main pulmonary artery is not enlarged with a straight segment. The left pulmonary artery is dilated and tapers rapidly. Occasionally, the large left hilum can be mistaken for lymphadenopathy. C, An atrial septal defect and pulmonary stenosis create a mixed pattern of shunt vascularity plus a large left pulmonary artery. The pulmonary annulus is hypoplastic causing the main pulmonary artery segment to be straight.

FIGURE 6-49 Different size of the right and left pulmonary arteries in valvular pulmonary stenosis. A, The convex large main pulmonary artery partially hides the left pulmonary artery. B, The right pulmonary artery (white arrow) has normal size in relation to the width of the trachea. The dilated left pulmonary artery (open arrow) is visible into the distal lung.

FIGURE 6-50 Pulmonary atresia. The lungs have decreased flow and are hyperlucent. The heart is overall enlarged, particularly the right atrium, from blood flowing right to left through a foramen ovale.

Cardiac-Gated Multidetector Computed Tomography

The normal tricuspid and pulmonary cardiac valves are not well visualized on cardiac-gated MDCT. Typical scanning protocols optimize arterial phase enhancement and the right-sided chambers contain either saline or a mixture of saline and contrast at the time of image acquisition. Only infrequently are the thin pulmonic or tricuspid valve leaflets visualized.

Valvular Pulmonary Stenosis

The most frequent cause of valvular pulmonary stenosis is a congenital defect. The valve usually is a membrane with a central hole but can be bicuspid or tricuspid. When this lesion calcifies, there has been previous endocarditis. Rare forms of pulmonary stenosis include tumor, thrombi, and aneurysms of the aortic sinus of Valsalva that prolapse through a membranous ventricular septal defect. Roughly 50% of patients with a carcinoid tumor that metastasized to the liver have pulmonary and tricuspid valve lesions. This tumor, with its vasoactive amines, causes endocardial thickening that leads to pulmonary stenosis, regurgitation, and tricuspid regurgitation.

Angiographically, the pulmonary valve is evaluated with a right ventriculogram. The leaflets have a domed appearance in systole, yet form the normal sinuses of Valsalva in diastole (Fig. 6-51). The jet of contrast through the lesion is in the center of the valve and points toward the main and left pulmonary arteries, producing poststenotic dilatation of these structures and sparing the right pulmonary artery. Although there is usually poststenotic dilatation of the pulmonary artery, the degree of dilatation does not correlate well with the severity of the gradient. When other lesions are present, as in tetralogy of Fallot, the pulmonary artery segment is concave.

FIGURE 6-51 Valvular pulmonary stenosis. A, Slight cranial angulation in the right anterior oblique projection places the plane of the pulmonary valve tangential to the x-ray beam and also demonstrates the origin of the right pulmonary artery. In general, a steeper cranial angulation is preferred because most congenitally malformed pulmonary valves have a vertical tilt. In this patient, the poststenotic dilatation of the main pulmonary artery is so massive that the left pulmonary artery could be seen only on the lateral projection. B, The symmetric doming of the pulmonary valve is confirmed in the lateral view. A small jet through the orifice attests to the severe stenosis. Note the small tricuspid annulus (arrows and arrowheads).

In some patients with valvular pulmonary stenosis, the infundibulum may be hyperkinetic with extreme narrowing in systole but a normal diastolic diameter (Fig. 6-52). The hyperkinetic systolic narrowing of the infundibulum occurs in its middle portion during contraction of the septal and parietal bands of the crista supraventricularis, giving an hourglass appearance to the infundibulum. After surgical or angioplasty repair of the stenotic valve, this subvalvular infundibular stenosis may be accentuated more because of the decreased afterload and, in rare instances, fatal right ventricular failure occurs because of complete occlusion of the hyperdynamic outflow tract: the suicidal right ventricle.

FIGURE 6-52 Dynamic subvalvular stenosis secondary to valvular stenosis. A, In late systole the infundibular stenosis almost occludes the region below the pulmonary valve (arrow). B, The lateral view shows the domed pulmonary valve, the infundibular stenosis, and the dilated main and left pulmonary arteries. In diastole, there was no infundibular stenosis.

The dysplastic pulmonary valve and the bicuspid valve represent less common types of valvular stenosis. The dysplastic pulmonary valve, which occurs in 15% of hearts with isolated pulmonary stenosis, has three cusps, which are thickened with unfused commissures. The bases of the sinuses of Valsalva are deformed and small as a result of excess tissue at the base of the leaflets (Fig. 6-53). The dysplasia also includes the pulmonary annulus, which is hypoplastic, as is the main pulmonary artery adjacent to the sinuses. Because the leaflets are stiff and thick, there is little change in their position throughout the cardiac cycle. This motion is in contrast to that in typical valvular stenosis with fused commissures, which shows a flexible domed membrane in systole and rounded sinuses of Valsalva in diastole. The sinuses in the dysplastic pulmonary valve are irregular and narrow in diastole; the thick leaflets produce an asymmetrically oriented orifice in systole. The recognition of the dysplastic pulmonary valve is important because unlike other types of valvular stenosis, it responds poorly to percutaneous valvuloplasty.

FIGURE 6-53 Dysplastic pulmonary valve. The sinuses of Valsalva are mildly deformed and eccentric in diastole. The annulus and infundibulum are slightly hypoplastic. The leaflets had little change in systole.

The bicuspid pulmonary valve appears similar to the bicuspid aortic valve, namely, unequal sinuses of Valsalva with fusion of one of the leaflets with a raphe, and a sinus of Valsalva occupying about half the valve circumference. Bicuspid pulmonary valves are present in about 50% of patients with tetralogy of Fallot. As part of this malformation, the annulus is often small, and the supravalvular region of the main pulmonary artery is hypoplastic. This combination of abnormalities produces an angiographic appearance that has been likened to “an open clamshell engulfing the infundibulum” (Fig. 6-54). In addition to the other features of tetralogy of Fallot, the areas of obstruction include the infundibular and supravalvular narrowing. There is usually no poststenotic dilatation of the distal main pulmonary artery.

FIGURE 6-54 Bicuspid pulmonary valve in tetralogy of Fallot. A, The length of the leaflets of the pulmonary valve appears greater than the width of the annulus. In addition to the doming of the leaflets, the infundibulum is hypoplastic. The left pulmonary artery is not seen because of competing flow through a left Blalock-Taussig shunt. B, On the lateral view, the hypoplastic infundibulum (arrows) is below the domed pulmonary valve. The left ventricle is opacified through the ventricular septal defect.

The annulus of the pulmonary valve may be hypoplastic. The leaflets of the valve and the adjacent main pulmonary artery are usually small and form part of the stenosis (Fig. 6-55).

FIGURE 6-55 Pulmonary valve annulus stenosis. A, The right ventriculogram show narrowing at the pulmonary valve and supravalvular stenosis involving the bifurcation of the right and left pulmonary arteries. A large trabeculation is seen laterally. B, On the lateral view in systole, the leaflets of the stenotic valve are domed and the annulus is small. The main pulmonary artery is mildly hypoplastic.

Congenital absence of the pulmonary valve is usually associated with a ventricular septal defect, annular pulmonary stenosis, and aneurysmal dilatation of the main pulmonary artery and the central part of both the right and left pulmonary arteries. This lesion can occur as an isolated entity but is associated with tetralogy of Fallot. The syndrome may also include a right aortic arch and peripheral pulmonary artery stenoses. The hilar pulmonary arteries may compress the bronchi, leading to hyperinflated lungs.

In Noonan syndrome, many cases have a dysplastic pulmonary valve. Hypertrophic cardiomyopathy commonly accompanies the pulmonary stenosis as part of the autosomal dominant syndrome.

Subvalvular Pulmonary Stenosis

Subpulmonary obstruction may occur either in the infundibulum or at the junction of the right ventricular body with the infundibulum. Primary infundibular obstruction is a rare malformation that may appear as either a fibrous band or a threadlike cavity through the infundibulum (Fig. 6-56). Discrete narrowing at the level of the crista supraventricularis divides the right ventricle into a main cavity and an infundibular chamber. In this situation, there is contraction of the infundibular chamber during systole, leading to more severe obstruction in addition to its fixed, discrete narrowing. The pulmonary valve may be normal but usually shows slight thickening, presumably because of the turbulence created by the obstruction.

FIGURE 6-56 Discrete infundibular pulmonary stenosis. A thin membrane is seen as a lucency between the body of the right ventricle and the infundibulum (arrow).

Other types of subpulmonary obstruction result from the muscular hypertrophy of the hypertrophic cardiomyopathies. The right ventricular outflow tract can show dynamic narrowing in idiopathic hypertrophic subaortic stenosis.

Infundibular stenosis frequently coexists with valvular stenosis. This type is not seen until after the patient is several months old, when other signs of right ventricular hypertrophy also become visible. Dynamic infundibular stenosis during systole may appear with a ventricular septal defect. This hypertrophy in the outflow tract decreases the left-to-right flow across the ventricular septal defect (Gasul phenomenon) and may cause stenosis that increases with age (Fig. 6-57).

FIGURE 6-57 Gasul phenomenon. The catheter has crossed the patent foramen ovale to enter the left ventricle (LV). In this lateral projection the body of the right ventricle (RV) has become opacified through the ventricular septal defect. In systole (A), the infundibulum (arrows) is markedly narrow, while in diastole (B), no subvalvular stenosis exists.

Hypoplasia of the crista supraventricularis is the main element in the infundibular stenosis in tetralogy of Fallot. The under-development of the infundibulum is associated with displacement of the crista above the ventricular septal defect. About half of patients with tetralogy of Fallot also have valvular pulmonary stenosis, in which case the pulmonary annulus is also small.

Obstructing muscular bands of the right ventricle, an abnormality that has also been called double-chambered right ventricle, may cause an obstruction either in the body of the right ventricle or higher in the infundibular region. These muscle bundles are seen as filling defects in the right ventricle, which may not contract. When the anomalous muscle occurs in the true right ventricular cavity, its location is variable; it may extend from the apex as a triangular mass on the posteroanterior projection or from the tricuspid valve to the junction of the infundibulum as a diagonal or wedge-shaped filling defect (Fig. 6-58).

FIGURE 6-58 Double-chambered right ventricle. A, A muscular bar (arrows) extends horizontally from near the tricuspid annulus to the anteroseptal wall and separates the body and infundibular sections of the right ventricle. B, A second type of obstructing muscular band (arrows) runs vertically on the free wall of the right ventricle and angles across the bottom of the infundibulum.

Supravalvular Pulmonary Stenosis

In supravalvular pulmonary stenosis, the pulmonary arteries are hypoplastic and may have segmental focal stenoses. In tetralogy of Fallot, there is frequently mild focal stenosis at the origin of the left and occasionally of the right main pulmonary artery. Occasionally the left pulmonary artery is absent. Rare causes of supravalvular pulmonary stenosis include Williams syndrome, carcinoid syndrome from an abdominal tumor with liver metastases, extrinsic stenoses from mediastinal fibrosis or tumor, and rubella.

These stenoses have a wide spectrum of morphologic appearance, from a short, discrete area of narrowing to long, diffuse hypoplastic segments involving several branches. There may be poststenotic dilatation with variable caliber of the peripheral artery. Gay and colleagues have classified the stenoses for surgical therapy according to their location. Type 1 has a single stenosis in the main pulmonary artery. Type 2 occurs at the bifurcation of the main with the right and left pulmonary arteries. Type 3 has only peripheral or branch stenoses. Type 4 is a mixture of the other types (Fig. 6-59).

FIGURE 6-59 Classification of supravalvular pulmonary stenosis. Type 1 is constriction of the main pulmonary artery. This stenosis can vary from a thin diaphragm to a diffusely hypoplastic artery. Type 2 is a constriction at the bifurcation of the main pulmonary artery that involves the origins of both the right and left main pulmonary branches. Type 3 is multiple peripheral stenoses with normal main, right, and left pulmonary arteries. The stenoses usually occur at the origins of peripheral branches and may have poststenotic dilatations. Type 4 is central and peripheral stenoses. The constrictions are multiple and involve any combination of main, right, and left central arteries with peripheral stenoses.

(Modified with permission from Gay BB, Franch RH, Shuford WH, et al.: The roentgenologic features of single and multiple coarctations of the pulmonary artery and branches, Am J Roentgenol 90:599-613, 1963.)

Diffuse pulmonary artery hypoplasia is a congenital malformation that may occur in isolation or with cardiac anomalies (Fig. 6-60). Centrally located segmental stenoses may be congenital (Fig. 6-61), whereas peripheral pulmonary arterial stenosis usually are secondary to other diseases (Fig. 6-62). Scarred lung from previous pneumonia, bullous emphysema, recanalized pulmonary emboli, and pulmonary arteritis from Takayasu disease are common causes.

FIGURE 6-60 Diffuse hypoplasia of central and peripheral pulmonary arteries.

FIGURE 6-61 Central pulmonary artery hypoplasia. A Blalock-Taussig shunt (right subclavian artery to right pulmonary artery) is anastomosed to a hypoplastic central pulmonary artery in a patient with pulmonary valve atresia.

FIGURE 6-62 Peripheral pulmonary artery stenosis. Selective injections in the right (A) and left (B) pulmonary arteries show multiple diffuse stenoses in the smaller parenchymal branches. Several distal branches are occluded.

Acquired supravalvular pulmonary stenosis in the form of pulmonary banding is created intentionally to reduce torrential pulmonary blood flow. The band is correctly positioned above the pulmonary annulus in the main pulmonary artery but may migrate distally causing unwanted branch stenosis (Fig. 6-63). A band placed too close to the pulmonary valve may cause leaflet thickening.

FIGURE 6-63 Pulmonary artery bifurcation stenosis. Transposition of the great arteries with congestive heart failure led to the placing of a pulmonary artery band. The band migrated distally, causing stenosis of the main, right, and left pulmonary arteries at the bifurcation. The catheter enters the left ventricle by crossing the atrial septal defect.

Pulmonary Regurgitation

Pulmonary regurgitation usually is acquired and results from pulmonary arterial hypertension. A congenital cause of pulmonary regurgitation is absence of the pulmonary valve, which is associated with tetralogy of Fallot. This malformation has large pulmonary arteries and a narrow pulmonary annulus creating a stenosis. Conversely, if a patient known to have tetralogy of Fallot paradoxically has large pulmonary arteries, he or she also has pulmonary regurgitation and an absent pulmonary valve.

The general rule that structures on each side of a regurgitant valve dilate is valid in chronic severe pulmonary regurgitation. The right ventricle and the central pulmonary arteries become large.

Tricuspid Stenosis

The chest film in tricuspid valve disease is quite variable. The abnormalities in tricuspid stenosis follow the principle that the chamber behind a severe stenosis is large. Although right atrial enlargement is always seen, the right ventricle and the left side of the heart frequently are also big because tricuspid stenosis is a late sequela of rheumatic mitral stenosis. The superior vena cava and azygos vein are enlarged. In congenital Ebstein anomaly, the film may be strikingly specific with its right atrial and right ventricular enlargement. The right atrium at the junction with the superior vena cava has an unusual rounded appearance (Fig. 6-64). In other types of tricuspid valve disease, the plain film shows nonspecific cardiac enlargement, occasionally with dilatation of the superior and inferior vena cava. In rheumatic heart disease, the features of mitral stenosis predominate: left atrial enlargement and pulmonary artery enlargement. Tricuspid valve calcification rarely may be seen at fluoroscopy. Tricuspid annular calcification has the same causes as mitral annular calcification, namely, dystrophic degeneration from aging and from chronic severe right ventricular hypertension (Fig. 6-65).

FIGURE 6-64 Ebstein anomaly. The round right heart border is a massively enlarged right atrium. A large right ventricle contributes most of the left side and apex of the cardiac silhouette. The pulmonary arteries are slightly enlarged, reflecting the atrial septal defect.

FIGURE 6-65 Tricuspid annular calcification. Arrows outline the tricuspid annulus. The mitral annulus is also calcified.

(Courtesy Robert E. Dinsmore, MD.)

Acquired tricuspid stenosis mainly results from rheumatic heart disease, although rare causes are right atrial tumors, the carcinoid syndrome, and pericardial and mediastinal masses external to the heart compressing the tricuspid valve. Rheumatic involvement of the tricuspid valve is invariably associated with enlargement of both the right atrium and right ventricle, thickened tricuspid leaflets that have diminished motion, and occasionally, some nodularity of the chordae. Although all these features may indicate rheumatic involvement in the absence of a pressure gradient, doming of the leaflets is consistently found when the stenosis is severe. Unlike stenosis of the semilunar valves, there is rarely a jet of contrast material through a stenotic valve.

Congenital tricuspid stenosis is extremely rare and is associated with severe hypoplasia of the right ventricle.

Box 6-7 summarizes the causes of tricuspid stenosis.

Tricuspid Regurgitation

Similar to mitral regurgitation, tricuspid regurgitation occurs when there is an abnormality in one or several parts of the tricuspid apparatus: the annulus, leaflets, chordae, papillary muscles, and right ventricular wall. Dilatation of the right ventricle and the tricuspid annulus secondary to pulmonary artery hypertension from mitral valve disease is the most common cause of acquired regurgitation (Fig. 6-66). When the abnormality causing the right ventricular enlargement (i.e., mitral stenosis) is corrected, right ventricular size usually returns to normal and the regurgitation ceases.

FIGURE 6-66 Tricuspid regurgitation. Two patients with tricuspid regurgitation evaluated with right ventriculography. A, The jet (arrows) of regurgitation is narrower than the tricuspid annulus, suggesting an element of stenosis. B, A wide, broad regurgitant stream filled both superior and inferior venae cavae and was grade 3 because the right atrium was denser than the right ventricle.

The grading of tricuspid regurgitation is similar to that of mitral regurgitation:

Diseases of the leaflets include rheumatic heart disease, the carcinoid syndrome, infective endocarditis, and trauma. Endocarditis from Staphylococcus typically destroys the tricuspid leaflets or causes multiple perforations and small, irregular vegetations on the ventricular side of the leaflets. Infection from Candida can produce large fungal tumors that partially obstruct blood flow (Fig. 6-67).

FIGURE 6-67 Tricuspid valve vegetation. A right atrial vegetation is outlined as a large circular mass attached to the tricuspid leaflets. A vegetation this large in the setting of endocarditis is typical of Candida.

Tricuspid valve prolapse results from redundancy of the leaflets and chordae and occurs in roughly 50% of patients with mitral valve prolapse, with or without Marfan syndrome. The identification of prolapse in the tricuspid valve is identical to that used with the mitral valve. It consists of defining the plane of the tricuspid annulus. Because in systole the normal tricuspid valve leaflets do not extend beyond this plane into the right atrium, when prolapse occurs, the tricuspid leaflets move to the right of this plane. These leaflets are large with multiple scallops and may create an eccentric jet, although usually a broad front of the regurgitant stream is visible in the right atrium.

Congenital causes of tricuspid insufficiency involve several parts of the tricuspid apparatus: dysplastic leaflets and chordal attachments without their displacement, Ebstein anomaly with leaflet displacement, or pulmonary atresia with an intact ventricular septum. Right ventricular infarction with ischemia or rupture of the papillary muscles appears as an akinetic or dyskinetic motion of the anterior, diaphragmatic, or septal walls of the right ventricle and is frequently associated with rupture of the interventricular septum.

Box 6-8 summarizes the causes of tricuspid regurgitation.

Ebstein Anomaly

Ebstein anomaly of the tricuspid valve is an uncommon malformation that may result in stenosis or regurgitation, or both. In most instances, there is an atrial septal defect or patent foramen ovale. The major anatomic features include displacement of the valve leaflets and their attachments toward the apex of the right ventricle, an “atrialized” portion of the right ventricle between the atrioventricular groove and the leaflet attachment, and dilatation of the right ventricle.

The attachment of the tricuspid leaflets is quite variable; a portion of the septal and posterior cusps usually adheres to the right ventricular wall. The large, redundant anterior leaflet originates several millimeters to several centimeters apically from the atrioventricular groove. Because of this displacement, the chordae tendineae and papillary muscles are also abnormal, ranging from those that are invisible angiographically to a discrete cylindrical muscle mass. The doming of the leaflets has a sail-like appearance during ventricular diastole. In extreme cases, the redundant leaflets may occlude the infundibulum during diastole.

The plain film of the chest in Ebstein anomaly shows a cardiac silhouette that varies from normal to strikingly enlarged. You should suspect this anomaly when you detect right atrial and right ventricular dilatation (Fig. 6-68). The contour of the large right atrium is round and occupies the right cardiac border. It is continuous with the superior vena cava and the right hemidiaphragm in the posteroanterior view. Dilatation of the right ventricle ordinarily is most visible on a lateral projection. However, if enlargement is massive, the right ventricle will contact the sternum and rotate the entire heart leftward. The result of this motion is that the frontal film will show a convexity in the upper cardiac border, which is not the left atrial appendage but rather the right ventricular outflow tract. Further dilatation of the right ventricle can cause it to become the entire left heart border. The size of the pulmonary vessels tends to reflect the amount of blood flowing through them. In those with atrial septal defects and moderate left-to-right shunts, the vascular markings are slightly large; in cyanotic patients with right-to-left flow across the interatrial shunt, the vessels tend to be small because of tricuspid stenosis.

FIGURE 6-68 Ebstein anomaly. A Hancock porcine tricuspid valve replacement and a surgically implanted epicardial cardiac pacemaker indicate that this patient had tricuspid stenosis or regurgitation and arrhythmias—complications of Ebstein anomaly. A, The right atrium is large because of its projection into the right lung and the distance between the tricuspid valve and the lateral right atrial wall. B, The retrosternal space is filled in by the large right ventricle.

You can make the angiographic diagnosis if the notch of the atrioventricular groove is separate from the displaced leaflet attachments (Fig. 6-69). This atrialized portion of the right ventricle is on the right atrial side of the tricuspid leaflets; it beats synchronously with the remainder of the ventricle because this segment contains contractile ventricular muscle. Occasionally, the wall of the atrialized portion of the ventricle may be only a fibrous sac and therefore be akinetic. The dilatation of the right atrium and right ventricle reflects the degree of tricuspid stenosis and regurgitation.

FIGURE 6-69 Billowing anterior leaflet in Ebstein anomaly. The anterior leaflet (arrowheads) extends into the outflow tract during systole. The posterior leaflet (arrow) is apically displaced. The dilated right ventricle forms the entire left border of the cardiac silhouette.

Patients with congenitally corrected transposition and a posteriorly placed right ventricle may have an associated Ebstein anomaly. Tricuspid regurgitation in congenitally corrected transposition should always raise the suspicion of a left-sided Ebstein anomaly; however, the tricuspid leaflet attachment in congenitally corrected transposition without Ebstein anomaly has slight apical displacement, so subtle degrees of the leaflet malformation may not be apparent.

Other Imaging Findings

Other imaging modalities nicely show the involvement of the different parts of the tricuspid apparatus. Two-dimensional echocardiography is the examination of choice for detecting the stenosis and quantitating the regurgitation with Doppler study. Imaging tumors, vegetations, mediastinal abnormalities, and Ebstein anomaly is appropriate with MRI, which has the advantage of showing the adjacent pericardium and mediastinum and demonstrating the regurgitant jet on magnetic resonance cineangiography.